9
Flow
control valve
Drain point
Filling point
Bypass
valve
Minimum 22 mm diameter
Tundish
(supplied)
Pressure
reducing
valve
(supplied)
Domestic
water
Heating
circuit
Return
Additional
expansion
vessel
(if required)
Boiler
Hot
Cold supply
HEATING SYSTEM DESIGN
• The
THELIA 30 E
boiler is compatible with any type
of installation.
• Heating surfaces may consist of radiators, con-
vectors or fan assisted convectors.
• Pipe sectional areas shall be determined in ac-
cordance with normal practices, using the output/
pressure curve
(diagram 4).
The distribution system
shall be calculated in accordance with the out-
put requirements of the actual system, not the maxi-
mum output of the boiler. However, provision shall
be made to ensure sufficient flow so that the tem-
perature difference between the flow and return
pipes be less than or equal to 20
°
C. The minimum
flow is 500 l/h.
• The piping system shall be routed so as to avoid
any air pockets and facilitate permanent venting
of the installation. Bleed fittings shall be provided
at every high point of the system and on all radia-
tors.
• The total volume of water permitted for the heat-
ing system depends, amongst other things, on the
static head in the cold condition. The expansion
vessel on the boiler is pressurised at 1 bar (corre-
sponding to a static head of 5 m w.g.) and allows
a maximum system volume of 150 litres for an aver-
age temperature of 75
°
C and a maximum service
pressure of 3 bar. This pressure setting can be modi-
fied at commissioning stage if the static head dif-
fers. An additional expansion vessel can be fitted
to the system if required, see
diagram 6.
• Provision shall be made for a drain valve at the
lowest point of the system.
• Where thermostatic radiator valves are fitted, not
all radiators must be fitted with this type of valve,
and in particular, where the room thermostat is
installed.
• In the case of an existing installation, it is
ESSENTIAL
that the system is thoroughly flushed prior to installing
the new boiler.
Filling the system
Provision must be made for filling the system at low
level. The use of a WRC approved filling loop is
strongly recommended, connected as shown in
diagram 6.
Diagram 6
Sch 173
DOMESTIC HOT WATER SYSTEM DESIGN
• Copper tubing must be used for the domestic
hot water system. Unnecessary pressure losses
should be avoided.
• The flow restrictor must be fitted in the cold wa-
ter inlet during installation. This limits the flow through
the boiler to a maximum of 12 l/min.
BOILER INSTALLATION
Statutory requirements
The installation of this boiler must be carried out by
a competent person in accordance with the rel-
evant requirements of the current issue of:
The Gas Safety (Installation and Use) Regulations
The Building Regulations
The local water company Byelaws
The Building Standards Regulations (Scotland)
The Health and Safety at Work Act
Sheet metal parts
WARNING. When installing or servicing this boiler,
care should be taken when handling the edges of
sheet metal parts to avoid the possibility of personal
injury.
Installing the boiler
Prior to starting work, the system must be thoroughly
flushed so as to eliminate any foreign bodies and
contaminants such as filings, solder particles, oil,
grease etc.
Note.
Solvent products could cause damage to the
system.
• Engage boiler upper part onto the hanging
bracket.
• Allow the boiler to seat down onto support plate.
• Fit filter and washers, strictly adhering to the se-
quential order and directions shown on
diagram 5.
• Connect the various couplings between boiler
and connection plate.
